def stem(self,w):
        """
        Get the stem of the word.
        @type w: string
        @param w: the word
        """
        stem=w
        while(1):
            if stem<>PorterStemmer().stem_word(w):
                stem=PorterStemmer().stem_word(w)
            else:
                break
        return stem

def lemma(self,w):
        """
        Get the lemma of the word.
        @type w: string
        @param w: the word
        """
        lemma=w
        while(1):
            if lemma<>WordNetLemmatizer().lemmatize(w):
                lemma=WordNetLemmatizer().lemmatize(w)
            else:
                break
        return lemma